The invention belongs to the field of clips or clamps for flexible sheeting materials such as plastic, fabric or canvas for tents, load covers or the like, which may be classified in Patent Office Classification 24/243.
In the past, flexible sheeting materials used as sails, tents, covers, tarpaulins for various applications such as construction projects, stored machinery, and railway and truck cargo, have been canvas. Grommets or eyelets punched through the material have been provided conventionally for gripping the flexible sheeting with rope or other fasteners. Their disadvantages are well-known, because making holes through the sheeting, even in the heaviest of canvas tarpaulins and the like, weakens them. Sooner or later they tear loose. Other disadvantages of grommets is that they are at fixed locations, allowing no option of gripping the sheeting somewhere else; and their use is generally limited to the edge portions of the sheeting because placing them in the center would make an undesirable hole and prevent it from being weather-proof. Plastic sheeting has replaced canvas for many of these uses. This is primarily because of lower cost but there are added advantages of light weight, compactness in storage, and resistance to rot and many chemicals. Most of the plastic sheeting materials are extremely tough and tear-resistant as long as they remain imperforate. But holes for grommets provide starting places for rips and make them unsuitable for heavy duty applications.
Attempts have been made to provide special clips for use in thin plastic sheeting materials which do not require the punching of holes, but none of these have been sufficiently satisfactory to become commercial to any significant extent. One such special clip is shown in Daniels U.S. Pat. No. 3,225,407 but this has a one-piece, non-adjustable jaw assembly incapable of being manually tightened, and because it requires constant tension loading to keep it fastened, it does not positively grip the flexible sheeting material for heavy duty use as does the clip of the present invention.